Weldment

ABSTRACT

A weldment wherein two members are joined by a weld bounded at a back portion by a back-up member providing improved weld penetration and prevention of undesirable conditions in the weld such as root gaps or blow-throughs. The back-up member may comprise an elongated element secured to the surface of one member and, more specifically, may be welded thereto by a continuous weld.

This is a division of application Ser. No. 566,500 filed Apr. 9, 1975,U.S. Pat. No. 3,986,784.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to welding and, in particular, to weldments andmethods of forming weldments wherein two plate members are joined by arcwelding.

2. Description of the Prior Art

In copending application for U.S. patent Ser. No. 469,337 of Thomas P.Casey, filed May 13, 1974, and owned by the assignee hereof, for aWeldment for Bulldozer Blades and Method and Apparatus Therefor, abulldozer blade is disclosed having a plurality of structural memberswelded together by means of an improved weldment comprising a groove anda contiguous dam formed on the surface of one member with a cornerportion of the other member disposed adjacent thereto. Common weld meansare provided for substantially filling the groove and securing themembers together. The groove and dam structure may be provided in anarcuate portion of the first member in a cold forming operation. Asbrought out in said application, such structure prevents undesirableblow-through during the welding process, effectively preventing crackformation which may cause premature failure of the welded structure.

SUMMARY OF THE INVENTION

The present invention comprehends a further improved weldment and methodof forming a weldment which eliminates the undesirable root gap orblow-through conditions of the prior art in a further improved andsimplified manner.

More specifically, the invention comprehends providing one memberintended to be welded to a second member, with a back-up meanseffectively preventing undesirable blow-through and the like, whereinthe back-up means is defined by an elongated element forming a weld stopon the first member surface at the rear of the weld space wherein thedesired welded joint is formed.

More specifically, the back-up means may comprise a rod welded to thesurface of the first member. In the illustrated embodiment the rod iswelded to an arcuate surface of the first member.

The second member may overlap the back-up element so as to partiallyoverlie the weld space and provide further improved welding of thesecond member to the first member.

The back-up element may comprise a rod welded to the first member as bya suitable welding operation. Where the first member is cylindricallyarcuate, the rod may extend coaxially thereof, and in the illustratedembodiment is disposed on the outer arcuate surface.

The back-up element may be relatively bulky so as to absorb the heat inthe welding operation and thereby provide a further improved weldment byavoiding burn-out of portions of the members being joined.

In the illustrated embodiment, the back-up element comprises a steel rodhaving a circular cross section which is continuously resistance weldedto the outer arcuate surface of the first member with the edge of thesecond member being brought closely to adjacent the arcuate surface inoverlapping relationship to the weld space defined cooperatively betweenback-up element and the weld members.

Thus, the present invention comprehends an improved weld which isextremely simple and economical of construction, while yet providing theabove described advantages.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingwherein:

FIG. 1 is a side elevation of a bulldozer blade having support membersjoined together by improved weldments embodying the envention;

FIG. 2 is an enlarged vertical section of one of the weldments;

FIG. 3 is a cross section similar to that of FIG. 2, but prior to thewelding operation;

FIG. 4 is a cross sectional view illustrating one method of securing theback-up element to the first weld member; and

FIG. 5 is a diagrammatic view of an apparatus for effecting suchsecuring of the back-up element from a rolled rod supply.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the exemplary embodiment of the invention as disclosed in thedrawing, a plurality of weldments, generally designated 10, embodyingthe invention are utilized in forming the structure of a device such asthe bulldozer blade generally designated 11. Such bulldozer bladesconventionally include cutting edge members 12 secured to the lower endof a pair of mold board plates 13 (one of which is illustrated in FIG. 1of the drawing). The mold board plates are secured to the oppositelateral ends of a push plate 14 which is structurally reinforced by aplurality of support members designated 15. The support members mayinclude end support members 16 and 17 and gusset members 18. The supportmembers further include a pair of channel support members 19 and 20, apair of angle support members 21 and 22, and a flat support member 23.As illustrated in FIG. 1, weldments 10 are utilized to secure therespective support members 19-23 together to define a strongreinforcement structure for the push plate 14.

The invention comprehends an improved arrangement of weldments 10 whichprovides a strong welded connection between the respective supportmembers.

One such weldment is illustrated in FIG. 2, it being understood thateach of the weldments 10 is substantially similar thereto. As shown inFIG. 2, support member 20 includes a cylindrical arcuate portion 24defining an outer surface 25 adapted to have an edge portion 26 ofsupport member 20 welded thereto in forming the weldment 10. Theinvention comprehends providing a back-up element 27 on surface 25 priorto the welding operation, as shown in FIG. 3. The back-up elementcomprises an elongated element which effectively prevents weld metalfrom being blown past the edge portion 26 during the welding operation,which may comprise a conventional arc welding operation. By preventingsuch blow-through, an improved weld 28 is obtained effectivelyautogenously bonding portion 26 of support member 22 to portion 24 ofsupport member 20.

In the illustrated embodiment, the back-up element comprises a rodwhich, as illustrated, may comprise a circular cross section rod, itbeing understood that any suitable cross section may be employed withinthe scope of the invention.

The back-up elements may be secured to the support member portion 24 bya welding operation as illustrated in FIGS. 4 and 5. As shown therein,the welding operation may comprise a continuous resistance weldingoperation effected by suitable resistance welding apparatus designated29. As shown in FIG. 5, the back-up element may comprise a rod providedfrom a rolled rod supply generally designated 30, delivered through asuitable straightener apparatus 31 and positioned in contact with thesupport member surface 25 and an electrode 32 of a welding head 33 ofthe welding apparatus. As shown in FIG. 4, an opposite electrode 34 maybe provided in the form of a wheel engaging the inner surface 35 of thesupport member portion 25.

Back-up element 27 is suitably positioned on surface 25 to permit theedge portion 26 of edge member 22 to extend beyond the back-up elementto partially overlie the weld space 36 conjointly defined by the back-upelement 27, edge portion 26 and arcuate portion 24. The extension ofedge portion 26 beyond the back-up element permits high tolerances inthe construction of the bull-dozer blade, substantially lowering thecost thereof, while yet permitting weld 10 to provide an effectivestrong weld at each of the joints. Thus, provision of the support memberportion 26, as shown in FIG. 3, adjacent weld space 36 permits aconventional arc welding operation to be effected to provide weld 28 ofFIG. 2. The back-up element 27 effectively prevents blow-through duringthe welding operation and effectively assures a full weld of the edgeportion 26 to the arcuate portion 24 along the entire extent of thejoint.

While the rod 29 may be continuously resistance welded to surface 25, aswill be obvious to those skilled in the art, any suitable means, such asspot welding, which effectively maintains the rod in abutment with thesurface 25 along the length thereof during the provision of weld 28 maybe employed. Maintained close conformity of the back-up element to thesupport member surface effectively avoids root gaps, thereby effectivelypreventing undesirable blow-through.

The improved weld 28 obtained in weldment 10 substantially reducesfailure of the structural members in such a bulldozer blade whichundergoes rigorous service in use. By eliminating such failures, timeconsuming and expensive repairs are obviated and the blade ismaintainedd structurally sound.

Once attached to the support member 20, rod 27 and support member form adesirable heat sink to absorb heat during the arc welding operation.This will effectively prevent burn-off of the edge portion 26 as mightotherwise occur during the arc welding operation where the back-upelement is not utilized.

In completing the construction of the bulldozer blade, a back cover 37may be provided outwardly of the support members as shown in FIG. 1,whereby a strong, low cost bulldozer blade is obtained.

The foregoing disclosure of specific embodiments is illustrative of thebroad inventive concepts comprehended by the invention.

I claim:
 1. The method of welding to a first member having a surfaceportion a second member having an edge portion disposed adjacent saidsurface portion, comprising the steps of: welding a back-up element tosaid first member to define a substantially continuous elongated weldstop along an arcuate part of said surface portion; disposing saidsecond member edge portion in engagement with said back-up element so asto cause said first member surface portion, said back-up element, andsaid second member edge portion to cooperatively define a weld spacewith the first and second members defining a rearwardly narrowing outerportion of said space terminating in a position of close proximity ofsaid first member to said second member, and defining a rearwardlywidening inner portion of said space between said position and theback-up element; and providing an arc weld substantially filling saidweld space and defining a continuous welded joint between said surfaceportion and said edge portion in both said outer and inner spaceportions bounded rearwardly by said weld stop, said first and secondmembers at said position defining a flow restricting passage forthrottling forces of the welding arc tending to urge the weld stop freeof said first member during the arc welding step.
 2. The method ofwelding the first member to the second member of claim 1 wherein saidback-up element comprises an elongated element and the step of weldingthe back-up element to the first member comprises the step ofcontinuously welding the back-up element along the length thereof. 3.The method of welding the first member to the second member of claim 1wherein said back-up element comprises an elongated element and the stepof welding the back-up element to the first member comprises the step ofcontinuously resistance welding the back-up element along the lengththereof.
 4. The method of welding the first member to the second memberof claim 1 wherein said back-up element comprises an elongated elementand the step of welding the back-up element to the first membercomprises the step of continuously arc welding the back-up element alongthe length thereof.
 5. The method of welding the first member to thesecond member of claim 1 wherein said member comprises portions of abulldozer blade assembly.